1. Field of the Invention
The present invention relates to a terminal for a coaxial cable and to a method for mounting such a terminal on a cable.
2. Description of the Related Art
Coaxial cables have been used for many purposes, including the transmission of high-frequency signals. The prior art coaxial cable includes a core, an inner insulation coating surrounding the core, a braided wire surrounding the inner insulation coating, and an outer insulation coating surrounding the braided wire. The prior art coaxial cable may be coupled to a printed circuit board. In this environment, the prior art coaxial cable is processed such that the core projects from a leading end of the inner insulation coating and the braided wire is folded back around the outer surface of the outer insulation coating at the end of the coaxial cable. A terminal is connected to the braided wire and enables connection of the coaxial cable to the printed circuit board. The terminal is provided with a barrel that is dimensioned to receive the coaxial cable. The cable is pushed into the barrel of the terminal, and the barrel is crimped into engagement with the cable.
The prior art terminals for the coaxial cables have no positioning means for positioning the terminal on the coaxial cable with respect to the longitudinal direction of the coaxial cable. Thus, the mount positions of the terminals may vary along the longitudinal direction, thereby causing a variation of high-frequency characteristics.
In view of the above, an object of the present invention is to provide a terminal for a cable, and to a method for connecting such a terminal to allow for a stable mounting of the terminal at a predetermined position on a leading end of the cable.
The subject invention is directed to a terminal that is mountable on a cable. The cable is comprised of a core and an insulation coating surrounding the core. A portion of the insulation coating is removed so that the core projects from the leading end of the insulation coating. The terminal comprises a barrel to be crimped into connection with a portion of the cable. The terminal further comprises a positioning portion to be held substantially in engagement with the cable. The positioning portion positions the terminal on the cable with respect to the longitudinal direction of the cable before the barrel is crimped into connection with the portion of the cable.
The terminal may be mountable on a coaxial cable comprised of a core surrounded by an inner insulation coating. The coaxial cable may be processed such that the core projects from the leading end of the inner insulation coating. The coaxial cable further comprises a shield layer in the form of a braided wire that surrounds the inner insulation coating, and an outer insulation coating that surrounds the braided wire. The braided wire that surrounds the inner insulation coating is folded back at least partly and is brought substantially into close contact with the outer surface of the outer insulation coating. The barrel portion is configured for crimped connection with a folded section of the shield layer of the coaxial cable.
The terminal may further comprise a cover that extends substantially continuously from the barrel portion to substantially cover the exposed core without being held in contact therewith.
According to a further preferred embodiment of the invention, the terminal may be mountable on a coaxial cable comprised of a core and an inner insulation coating surrounding the core. The coaxial cable is processed such that the core projects from the leading end of the inner insulation coating. The coaxial cable further comprises a braided wire surrounding the inner insulation coating and an outer insulation coating surrounding the braided wire. The braided wire is folded back and brought into close contact with the outer surface of the outer insulation coating. The terminal comprises a barrel for crimped connection with the folded section of the braided wire. A cover extends continuously from the barrel and covers the core without being held in contact therewith. The terminal further comprises a positioning portion to be held in engagement with the coaxial cable for positioning the terminal on the coaxial cable with respect to the longitudinal direction of the coaxial cable.
Accordingly, when the terminal is mounted on the coaxial cable, the positioning portion is brought into contact with the coaxial cable to position the terminal with respect to the longitudinal direction of the coaxial cable. The barrel then is crimped into connection with the folded section of the braided wire in this state, with the result that the terminal can be stably mounted at a predetermined position on the coaxial cable. Since the terminal is stably mounted and the cover covers the core over a predetermined length, an electrical capacity between the core and the terminal is stabilized, thereby providing stable high-frequency characteristics.
Preferably, the cover is integrally or unitarily formed with one or more legs for mounting the terminal on a printed circuit board. Accordingly, the legs of the cover enable the terminal to be mounted easily on the printed circuit board.
Preferably, the legs are provided with one or more embossed portions for strengthening the legs and/or for locking the legs in corresponding mount holes of the circuit board. The legs also may be provided with stepped portions that engage the circuit board upon insertion of the legs into mount holes of the printed circuit board.
The barrel may be formed with at least one inwardly projecting biting portion for biting in a portion of the cable, preferably in the braided wire of the shield layer. Accordingly, the biting portion bites into the braided wire when the barrel is crimped into connection with the braided wire, to further resist disengagement of the barrel from the coaxial cable.
A projection of the biting portion may be shorter than the positioning portion to prevent the biting portion from interfering with the insertion of the cable into the terminal. Accordingly, the coaxial cable can be inserted smoothly into the terminal without interference with the biting portion.
Most preferably, the terminal is constructed such that the cable can be inserted along its longitudinal direction into the terminal from the barrel side up to the cover. The positioning portion is formed by cutting the cover and bending the cut portion to engage the front end of the outer insulation coating, which is a starting position of the folded section of the shield layer. Accordingly, when the cable is inserted into the terminal from the barrel side and the leading end of the positioning portion comes into contact with a portion of the folded section of the braided wire, any further insertion of the cable is restricted. As a result, the terminal can be positioned automatically on the cable with respect to the longitudinal direction of the cable.
According to a further preferred embodiment, the biting portion and the positioning portion are arranged substantially opposing to each other along an arrangement direction of the cable.
According to the invention, there is further provided a method for mounting a terminal on a cable. The cable comprises a core and an insulation coating surrounding the core. The cable may be processed by removing a portion of the insulation coating, such that the core projects from the leading end of the insulation coating. The method comprises positioning the terminal on the cable with respect to the longitudinal direction of the cable by bringing a positioning portion substantially in engagement with the cable, and crimping a barrel portion into connection with a portion of the cable.
These and other objects, features and advantages of the present invention will become more apparent upon a reading of the following detailed description and accompanying drawings.